A late Israel Folau try secured the Waratahs a crucial 21-15 victory over the Stormers in Sydney on Saturday.
Folau exploited a gap in the Stormers defence and beat two defenders, from close range, to score what proved to be the match-winning try in the 77th minute.
The Stormers were leading 15-11, up to that stage, but showed little enterprise on attack and paid a costly price for being too defensive in the game's latter stages.
The match was a dour affair as both sides spent large periods kicking away possession and most of the play was restricted to the forwards.
The visitors did most of the attacking during the opening quarter but had little to show for their efforts. They spent plenty of time inside the Waratahs' half but their only points came via a penalty from Joe Pietersen in the 16th minute.
The Waratahs struck back with a try from Cam Crawford in the 24th minute. The speedster, who scored a hat-trick against the Kings last weekend, dotted down after claiming an offload from Folau, who rose highest after Bernard Foley launched a cross-kick inside the Stormers' 22.
On the stroke of half-time, Brendan McKibbin added a penalty which meant the 'Tahs led 8-3 at the changeover.
But the Stormers soon regained the lead when Pietersen succeeded with two successive three-pointers inside the first 10 minutes of the second half.
The second half briefly threatened to turn into a kicking duel, between Pietersen and McKibbin, as both sides opted to kick at posts whenever they were within striking distance.
McKibbin put the Waratahs back in front with a penalty in the 53rd minute and Pietersen added two of his own within a 10 minute period shortly afterwards.
The introduction of Berrick Barnes, as a replacement for Foley, seemed to ignite the Waratahs, who were more daring on attack during the Wallaby's 20 minute cameo on the field.
Barnes made the final pass for Folau's try and added to the Stormers' woes when he landed a penalty from the halfway line, in injury time, to put the final nail into the visitors' coffin.
Tries: Crawford, Folau
Pen:McKibbin 2, Barnes
Pen: Pietersen 5
Waratahs: 15 Israel Folau, 14 Cam Crawford, 13 Adam Ashley-Cooper, 12 Rob Horne, 11 Peter Betham, 10 Bernard Foley, 9 Brendan McKibbin, 8 Wycliff Palu, 7 Michael Hooper, 6 Dave Dennis (capt), 5 Kane Douglas, 4 Sitaleki Timani, 3 Sekope Kepu, 2 Tatafu Polota-Nau, 1 Benn Robinson.
Replacements: 16 John Ulugia, 17 Paddy Ryan, 18 Will Skelton, 19 Mitchell Chapman, 20 Matt Lucas, 21 Berrick Barnes, 22 Drew Mitchell.
Stormers: 15 Joe Pietersen, 14 Gio Aplon, 13 Juan de Jongh, 12 Jean de Villiers (c), 11 Bryan Habana, 10 Gary van Aswegen, 9 Dewaldt Duvenage, 8 Duane Vermeulen, 7 Rynhardt Elstadt, 6 Siya Kolisi, 5 Andries Bekker, 4 Eben Etzebeth, 3 Frans Malherbe, 2 Deon Fourie, 1 Steven Kitshoff.
Replacements: 16 Scarra Ntubeni, 17 Pat Cilliers, 18 Don Armand, 19 Nizaam Carr, 20 Louis Schreuder, 21 Elton Jantjies, 22 Gerhard van den Heever.
Referee: Chris Pollock